Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2018	$ 1	$ 223,440	$ (207,330)	$ 16,111
Beginning Balance, (in shares) at Dec. 31, 2018	310,330
Share-based compensation expense		67		$ 67
Issuance of common stock upon vesting of restricted stock units (in shares)	27			27
Issuance of common stock under ESPP		1		$ 1
Issuance of common stock under ESPP (in shares)	36
Net loss			(2,635)	(2,635)
Stockholders' Equity Attributable to Parent, Ending Balance at Mar. 31, 2019	$ 1	223,508	(209,965)	13,544
Ending Balance, (in shares) at Mar. 31, 2019	310,393
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2019	$ 2	224,741	(219,160)	$ 5,583
Beginning Balance, (in shares) at Dec. 31, 2019	550,736			550,736
Share-based compensation expense		70		$ 70
Issuance of common stock under ESPP (in shares)	0
Fractional shares issued due to reverse stock split	7,692
Issuance of common stock upon exercise of warrants		286		286
Issuance of common stock upon exercise of warrants (in shares)	1,057,512
Issuance of common stock in public offerings		6,035		6,035
Issuance of common stock in public offerings (in shares)	955,613
Net loss			(2,414)	(2,414)
Stockholders' Equity Attributable to Parent, Ending Balance at Mar. 31, 2020	$ 2	$ 231,132	$ (221,574)	$ 9,560
Ending Balance, (in shares) at Mar. 31, 2020	2,571,553			2,571,553